KRAS and undifferentiated pleomorphic sarcoma: A previous study by Blum et al. reported that a mouse model of MyoD-expressing cells with activation of oncogenic K-Ras and p53 deletion in adult mice led to the formation of undifferentiated pleomorphic sarcoma (UPS), as opposed to RMS (Blum et al., 2013), and Doyle et al. reported that p53R172H/+ resulted in the rapid development of UPS in the setting of an activating K-Ras mutation (Doyle et al., 2010).